Monte Carlo
Gottlieb, 1987The stargate ramp on a Gottleib Monte Carlo is stuck on. I've replaced the transistor (which was fried) and it is still stuck on. Since I didn't know the pre-driver transistor, I unplugged A3J3 to see if it would shut off. It didn't and I noticed that the resistors on the coil are laid out differently than for the flippers and wonder if that is the problem. Could someone check to see if this is correct or not?
Vid,
The Gottlieb Stargates usually use a flipper coil with an EOS switch so it has lots of power to move it and then power down just to hold it.
But then, you probably knew that.
Quoted from vid1900:1. Did it ever work, or did you buy it broken?
2. Does the schematic show a dual wound coil?
3. Is it the correct coil for that mech location?
4. Did you check the diodes with your meter?
Thanks for the feedback Vid.
1. I assumed it worked at some point (when it was new?), but when I got it, the coil didn't work (stuck off). I tested and replaced the transistor that drives it (2N3055). After that, it was stuck on.
2. The manual (which I attached a photo of in the second post) shows a single wound coil, but I'm pretty sure it should be a double wound (see post 4)
3. The coil from the schema is A-17875. The coil in the game is AO-25 500/34 5050. According to Marcos (http://www.marcospecialties.com/pinball-parts/A-17875), A-17875:
24-560/31-1100 windings
2.8/40 ohms resistnace (no diode)
Wico 03-314900
03-3149
03-3116
D-15361 bobbin
So. . . no? Any chance that this coil is a suitable replacement or the correct coil is the way to go?
4. Yes. They were good.
The Manual's exploded view shows only two wires because those are the two that go to the EOS switch (Also part of that drawing). You still notice it is a 3 lug coil. It does not show the two wires coming from the playfield loom which would attach to the coil lugs too.
The AQ flipper coil is a Bally 50V flipper coil, so it would depend on if the Stargate is getting 50V flipper power or not. I believe that era Gottlieb is instead, the lower voltage only (28V?). So, while it MAY work (Be strong enough), it would be better to get the correct coil and wire it according to the Schematic wire color wise.
If its still stuck on, you probably have a shorted solenoid drive transistor after possibly the coil being wired backwards (as far as diode orientation goes).
Quoted from crlush:Did you check the transistor under the playfield?
That is the one that was blown and replaced. I tested it again and it is shorted -- going to replace it and double check how the existing coil is wired.
Quoted from CactusJack:The Manual's exploded view shows only two wires because those are the two that go to the EOS switch (Also part of that drawing). You still notice it is a 3 lug coil. It does not show the two wires coming from the playfield loom which would attach to the coil lugs too.
The AQ flipper coil is a Bally 50V flipper coil, so it would depend on if the Stargate is getting 50V flipper power or not. I believe that era Gottlieb is instead, the lower voltage only (28V?). So, while it MAY work (Be strong enough), it would be better to get the correct coil and wire it according to the Schematic wire color wise.
If its still stuck on, you probably have a shorted solenoid drive transistor after possibly the coil being wired backwards (as far as diode orientation goes).
This is very helpful -- thanks for info! I've ordered a new coil.
Quoted from crlush:there's another one on the driver board
Do you happen to know which one?
Quoted from lyonsden:If I'm reading this correctly, I'm guessing L13 is the pre-trigger for it? Sorry for the lame questions -- I haven't worked on a sysetm80 (or many Gottleibs) before.
those are lights, just fixed one a couple months ago but cant remember where, best to trace the wire up to the head and find it on the board then follow the trace to the transistor. make sure you tighten the screws on the transistors on the driver board also, I was having problems because the screws were loose and it wasn't grounding.
Quoted from crlush:those are lights, just fixed one a couple months ago but cant remember where, best to trace the wire up to the head and find it on the board then follow the trace to the transistor. make sure you tighten the screws on the transistors on the driver board also, I was having problems because the screws were loose and it wasn't grounding.
Thanks, again. For another lame question, I'm having a hard time figuring out which wire to trace.
The coil wires seem to run to the transistor and the EOS switch, as well as a fuse block. I'm having a hard time figuring out where the signal comes from to trigger the transistor. (I'm starting to think that Gottleibs were built by crazy people.)
IMG_5880 (resized).JPG
IMG_5881 (resized).JPG
IMG_5879 (resized).JPG
IMG_5882 (resized).JPG
I might be wrong on L13, check Q14 transistor on driver board, if your not sure how to check if its good or bad you can compare readings from one of the transistors next to it. if its good then one of the wires for the ramp run up to the driver board, I usually just right down the colors and look for it at the wires leading into the driver board.
I have a similar problem with my left ramp solenoid. It will never energize. It's been a while and I could be wrong, but I read that a shot up the left ramp and down the habitrail is supposed to energize that solenoid and lift the ramp.
I have replaced one or two of the bad transistors under the playfield. I have replaced the A17875 solenoid. It is still not working. I haven't dug into it any further - too many Project Pins!
I THINK that this is the original solenoid. I can't be 100% certain because there are no markings on it:
Solenoid A17875 Old (resized).jpg
This is the new A17875 solenoid, installed.
Solenoid A17875 New (resized).jpg
Anyway, both have only one diode on them.
Quoted from Pecos:I have a similar problem with my left ramp solenoid. It will never energize. It's been a while and I could be wrong, but I read that a shot up the left ramp and down the habitrail is supposed to energize that solenoid and lift the ramp.
its supposed to lift when you start a game and stay up when you roll under it and lock a ball then it lowers and when you make the ramp shot it will raise back up. the transistor for the ramp under playfield is the one that is on a bracket by itself.
Quoted from crlush:I might be wrong on L13, check Q14 transistor on driver board, if your not sure how to check if its good or bad you can compare readings from one of the transistors next to it. if its good then one of the wires for the ramp run up to the driver board, I usually just right down the colors and look for it at the wires leading into the driver board.
I checked Q14 and it has the same readings that the other transistors in the row. I used the method in: http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Controlled_Lamp_Issues
Testing an MPS-U45 transistor (or NDS-U45 or CEN-U45 which are equivalents).
Set your DMM to diode test
Measure on the solder side of the board, with J5 and J6 oriented toward you
Place the red lead of your DMM on the center leg
Place the black probe on left leg. That leg should read about 1.3
Move the black probe to the right leg. That leg should read about .7
Readings close to these, or even similar to adjacent like components, indicate a good component. Failure to obtain these readings means the component has failed.
Quoted from Pecos:I have a similar problem with my left ramp solenoid. It will never energize. It's been a while and I could be wrong, but I read that a shot up the left ramp and down the habitrail is supposed to energize that solenoid and lift the ramp.
I have replaced one or two of the bad transistors under the playfield. I have replaced the A17875 solenoid. It is still not working. I haven't dug into it any further - too many Project Pins!
I THINK that this is the original solenoid. I can't be 100% certain because there are no markings on it:This is the new A17875 solenoid, installed.
Anyway, both have only one diode on them.
Thanks for these pictures. Any chance you could take one of the transistor that is controlling the coil? I have it in my photos above for reference.
If you have tracked it down to that transistor then you have gotten further than I have. My transistor tests bad, again. I won't be putting another one in until I check the rest of the circuit for problems.
If I am testing it correctly and if it is the right solenoid, my old solenoid tests good. lyonsden, you are welcome to it it you want it. PM me.
Quoted from G-P-E:Are you testing that transistor with or without the wires still attached?
I tested the one under the playfield without wires attached. The one on the power driver board was tested in place.
Quoted from Pecos:If you have tracked it down to that transistor then you have gotten further than I have. My transistor tests bad, again. I won't be putting another one in until I check the rest of the circuit for problems.
If I am testing it correctly and if it is the right solenoid, my old solenoid tests good. lyonsden, you are welcome to it it you want it. PM me.
That is super awesome of you to offer! I just placed an order for one, so I won't need it. However, it would be great to meet another pinball person in Tucson (in case we haven't met.)
Got this sorted out. All transistors mounted on the PF are 2N3055 EXCEPT the one for the ramp, which is 2N5879. The former is NPN and the latter PNP. I was using NPNs as I checked a different transistor for the part number. 
Put in the correct transistor (2N5884 as a replacement for 2N5879) and things are working correctly.
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Sana'a
Lake Forest, CA
That explains a lot. I read somewhere that ALL of those transistors were 2N3055 so that is what I installed. I am looking forward to seeing that ramp rise from the dead soon.